Dishwasher

ABSTRACT

The present disclosure provides a dishwasher having an improved basket pull-out structure. The dishwasher includes: a tub; a basket arranged inside the tub for loading dishes; and a draw-out unit arranged on either side of the basket for guiding the basket to be drawn out forward from the tub, wherein the draw-out unit includes first, second, and third rails, a plurality of first balls placed between the first and second rails, and a plurality of second balls placed between the second and third rails, and wherein the plurality of first balls and the plurality of second balls are arranged in vertical direction. According to the present disclosure, a slim draw-out unit may be provided by aligning ball bearings in vertical direction, thereby increasing the space utility of the dishwasher.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. §119(a) of a Koreanpatent application filed on Jan. 6, 2014 in the Korean IntellectualProperty Office and assigned Serial No. 10-2014-0001522, the entiredisclosure of which is incorporated hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to dishwashers, and more particularly toa dishwasher with an improved pull-out structure of baskets.

BACKGROUND

In general, a dishwasher is a device for cleaning dishes by sprayinghigh-pressure water at the dishes and typically runs washing, rinse, anddry cycles. The dishwasher removes dirt from the dishes by sprayingwater without throwing in detergent during a preliminary washing cycle,and cleans dishes by spraying water and simultaneously throwing indetergent in the main washing cycle. The dishwasher rinses the detergentfrom dishes by spraying water in the rinse cycle, and dries them in thedry cycle.

In the tub of the dishwasher in which dish washing is conducted, basketsfor loading washable items (or dishes) are contained. In order for theuser to conveniently load or remove the washable items, the baskets areinstalled to be drawn out forward from the tub. Draw-out units areinstalled on either side of the basket to guide the movement of thebasket.

The draw-out unit commonly includes multiple rails, and the basket maybe moved while being rolled along the rail with e.g., a roller. However,moving with the roller causes serious friction and big noise.Furthermore, due to vulnerability to shaking, the roller may derail,thus weakening the durability.

Accordingly, a draw-out unit that guides the basket with ball bearingsinstead of the roller has recently been introduced. However, such adraw-out unit also has a problem that the supporting structure of theball bearing is weak in durability.

Moreover, the use of the multiple rails increases the volume of thedraw-out unit, thereby inevitably reducing the space that holds washableitems.

SUMMARY

The present disclosure provides a dishwasher having a draw-out unit thatuses ball bearings with good durability.

The present disclosure also provides a dishwasher that increases spaceefficiency with a small volume draw-out unit.

In accordance with an aspect of the present disclosure, a dishwasher isprovided. The dishwasher includes: a tub; a basket arranged inside thetub for loading dishes; and a draw-out unit arranged on either side ofthe basket for guiding the basket to be drawn out forward from the tub,wherein the draw-out unit includes first, second, and third rails, aplurality of first balls placed between the first and second rails, anda plurality of second balls placed between the second and third rails,and wherein the plurality of first balls and the plurality of secondballs are arranged in vertical direction.

The first, second, and third rails may each be arranged to form a crosssection including a coupling unit that extends in the vertical directionand upper and lower ends that bend toward one side.

The upper and lower ends of each of the first, second, and third railsmay bend toward one side of the coupling unit in an identical form.

The coupling unit of the first rail may be formed to extend longer thanthe coupling unit of the second rail in the vertical direction, and thecoupling unit of the second rail may be formed to extend longer than thecoupling unit of the third rail in the vertical direction.

The first and second rails may be arranged such that the upper end ofthe second rail is placed below the upper end of the first rail and thelower end of the second rail is placed above the lower end of the firstrail, and the second and third rails may be arranged such that the upperend of the third rail is placed below the upper end of the second railand the lower end of the third rail is placed above the lower end of thesecond rail.

The plurality of first balls may include at least one first upper ballplaced between the upper end of the first rail and the upper end of thesecond rail, and at least one first lower ball placed between the lowerend of the first rail and the lower end of the second rail, and theplurality of second balls may include at least one second upper ballplaced between the upper end of the second rail and the upper end of thethird rail, and at least one second lower ball placed between the lowerend of the second rail and the lower end of the third rail.

The dishwasher may further include a first retainer for holding the atleast one first upper ball and the at least one first lower ball; and asecond retainer for holding the at least one second upper ball and theat least one second lower ball.

The upper and lower ends of the second rail may be arranged toward thesame direction as that of the upper and lower ends of the first rail,and the upper and lower ends of the third rail may be arranged towardthe opposite direction of that of the upper and lower ends of the firstrail.

The draw-out unit may include a first retainer placed between the firstand second rails, and a second retainer placed between the second andthird rails.

The first retainer may include a plurality of first ball installationunits that hold the plurality of first balls, and the second retainermay include a plurality of second ball installation units that hold theplurality of second balls.

The first retainer may be installed to be able to move along the firstrail, and the first rail may include a first fastening rib forpreventing the first retainer from deviating from the first rail, andthe second retainer may be installed to be able to move along the secondrail, and the second rail may include a second fastening rib forpreventing the second retainer from deviating from the second rail.

The first rail may be attached onto the inner side of the tub, the thirdrail may be coupled with the basket, and the second rail may be placedbetween the first and third rails.

The basket may include a coupling unit on each side, and the couplingunit may be coupled with the third rail to movably support the basket.

The coupling unit may include a coupling projection that protrudestoward the third rail, and the third rail may include a coupling grooveinto which the coupling projection is fit.

The dishwasher may further include: a coupling member detachably coupledwith the third rail so as to fasten the coupling projection fit into thecoupling groove.

In accordance with another aspect of the present disclosure, adishwasher is provided. The dishwasher includes: a tub; a basketarranged inside the tub for loading dishes; and a first rail fixed ontoan inner wall of the tub; a second rail installed to be able to movealong the first rail; a third rail installed to be able to move alongthe second rail and coupled with the basket; a first ball bearing placedbetween the first and second rails and arranged to be able to move alongthe first rail; and a second ball bearing placed between the second andthird rails and arranged to be able to move along the second rail.

The first ball bearing may include at least one first ball and a firstretainer for holding the at least one first ball, and the second ballbearing may include at least one second ball and a second retainer forholding the at least one second ball.

The at least one first ball and the at least one second ball may bearranged in vertical direction.

In accordance with another aspect of the present disclosure, adishwasher is provided. The dishwasher includes: a tub; a basketarranged in the tub for loading dishes; and a draw-out unit installedbetween the tub and the basket, including a plurality of rails forguiding movement of the basket, wherein the plurality of rails include afirst rail attached to the tub, a second rail arranged to have one sidebe adjacent to the first rail, and a third rail having one side beadjacent to the second rail and the other side coupled with the basket,and wherein the first rail is formed to extend longer than the secondrail in the vertical direction, and the second rail is formed to extendlonger than the third rail in the vertical direction.

The plurality of rails may each be formed to have a cross section thatincludes a coupling unit that extends in the vertical direction andupper and lower ends that bend from the coupling unit in the samedirection.

The first and second rails may be arranged to have their upper and lowerends toward the basket, and the third rail may be arranged to have itsupper and lower ends toward the opposite direction compared to the firstand second rails.

The draw-out unit may include a first ball bearing placed between thefirst and second rails, and a second ball bearing placed between thesecond and third rails.

The first ball bearing may include a first upper ball placed between theupper end of the first rail and the upper end of the second rail, and afirst lower ball placed between the lower end of the first rail and thelower end of the second rail, and the second ball bearing may include asecond upper ball placed between the upper end of the second rail andthe upper end of the third rail, and a second lower ball placed betweenthe lower end of the second rail and the lower end of the third rail.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the disclosure

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present disclosurewill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIG. 1 illustrates a dishwasher, according to an embodiment of thepresent disclosure;

FIG. 2 illustrates a dishwasher with baskets drawn out, according to anembodiment of the present disclosure;

FIG. 3 is an exploded view of a dishwasher into a tub, a basket, and adraw-out unit, according to an embodiment of the present disclosure;

FIG. 4 is an exploded view of a draw-out unit of a dishwasher, accordingto an embodiment of the present disclosure;

FIG. 5 is a cross-sectional view of a draw-out unit of a dishwasher,according to an embodiment of the present disclosure; and

FIG. 6 illustrates combination of a draw-out unit and basket of adishwasher, according to an embodiment of the present disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The present disclosure will now be described more fully with referenceto the accompanying drawings, in which exemplary embodiments of thedisclosure are shown. The disclosure may, however, be embodied in manydifferent forms and should not be construed as being limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the concept of the disclosure to those skilled in the art. Likereference numerals in the drawings denote like elements, and thus theirdescription will be omitted. In the description of the presentdisclosure, if it is determined that a detailed description ofcommonly-used technologies or structures related to embodiments of thepresent disclosure may unnecessarily obscure the subject matter of theinvention, the detailed description will be omitted. It will beunderstood that, although the terms first, second, third, etc., may beused herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section.

The present disclosure will now be described more fully with referenceto the accompanying drawings, in which exemplary embodiments of thedisclosure are shown.

The disclosure may, however, be embodied in many different forms andshould not be construed as being limited to the embodiments set forthherein; rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the concept of thedisclosure to those skilled in the art. Like reference numerals in thedrawings denote like elements, and thus their description will beomitted.

In the description of the present disclosure, if it is determined that adetailed description of commonly-used technologies or structures relatedto embodiments of the present disclosure may unnecessarily obscure thesubject matter of the invention, the detailed description will beomitted.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section.

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to the like elements throughout.

FIG. 1 illustrates a dishwasher 1, according to an embodiment of thepresent disclosure, and FIG. 2 illustrates the dishwasher 1 with basketsdrawn out, according to an embodiment of the present disclosure.

The dishwasher 1 may include a case 10 that forms the exterior, and atub 20 formed inside the case 10. The front side of the case 10 may beopened to load dishes in the tub 20 or withdraw them from the tub 20. Adoor 30 may be movably combined with the case 10 to open/close the tub20.

The case 10 may have a form of a box, as shown in FIG. 1. However, theform of the case 10 is not limited to what is shown in FIG. 1, and maybe in the form of a column or a multi-sided pillar, or in the form of apolyhedral box other than the cubical box. In addition, the dishwasher 1may be implemented in other various forms that may be applied as theexterior of the dishwasher 1.

The door 30 may be moved in a certain direction to open or close the tub20. There may be hinges (not shown) on an edge of the door 30 to rotatethe door 30 in a certain direction.

The door 30 is installed in front of the tub 20, and the user may openthe door 30 and load washable items inside the tub 20. A handle (notshown) may be attached onto the door 30 to help the user easily open orclose the door 30. A detergent container 31 may be arranged on the innerside of the door 30 for containing detergent.

The tub 20 may have a form that corresponds to the shape of the case 10.The tub 20 may thus be in the form of a box, but is not limited thereto.The tub 20 may be in the form of a column or a multi-sided pillar, or inthe form of a polyhedral box other than the cubical box. However, thetub 20 may not be necessarily formed to correspond to the shape of thecase 10.

Inside of the tub 20, there may be baskets 40, 45 for loading dishes anda spraying unit 50 for spraying water. The spraying unit 50 may spraywater at the dishes loaded in the baskets 40, 45 to clean the dishes byusing at least one nozzle (not shown).

The baskets 40, 45 may be wire racks formed of wires so that water doesnot pool but drains. The baskets 40, 45 may include an upper basket 40arranged on the upper part of the tub 20 and a lower basket 45 arrangedon the lower part of the tub 20. For convenience of explanation, theupper basket 40 will now be just called basket.

As shown in FIG. 2, the basket 40 may be drawn out forward from the tub20. For this, the dishwasher 1 may include a draw-out unit 100 thatguides the basket 40 to be drawn out forward from the tub 20. The usermay load dishes in the basket 40 drawn out with the draw-out unit 100and push the basket 40 back to the inside of the tub 20 to clean thedishes. After dish washing is finished, the user may draw out the basket40 forward from the tub 20 and take out the cleaned dishes.

FIG. 3 is an exploded view of the dishwasher 1 into the tub 20, thebasket 40, and the draw-out unit 100, according to an embodiment of thepresent disclosure. For convenience of explanation, only one basket 40is shown and the top and bottom faces of the tub 20 are omitted in FIG.3.

To have the basket 40 supported by the tub 20, the draw-out unit 100 maybe installed between the tub 20 and the basket 40. As shown in FIG. 3, apair of draw-out units 100 are attached on the inner sides of the tub 20and coupled with both sides of the basket 40.

The basket 40 may include a pair of coupling units 60 on the sides ofthe basket 40 to correspond to the pair of draw-out units 100. Thecoupling unit 60 may be coupled with the draw-out unit 100 for movablysupporting the basket 40. Specifically, one side of the draw-out unit100 is attached onto the inner side of the tub 20 and the other side iscoupled with the basket 40.

To draw out the basket 40 as much distance as desired, the draw-out unit100 may include multiple rails. Hereinafter, for convenience ofexplanation, one draw-out unit 100 and one coupling unit 60 aredescribed because the pair of draw-out units 100 and the pair ofcoupling units 60 are identically configured, respectively.

FIG. 4 is an exploded view of the draw-out unit 100 of the dishwasher 1,according to an embodiment of the present disclosure, and FIG. 5 is across-sectional view of the draw-out unit of 100 a dishwasher 1,according to an embodiment of the present disclosure.

The draw-out unit 100 may include a first rail 110, a second rail 120,and a third rail 130 for enabling double withdrawal. The first rail 110may be fixed onto the inner side of the tub 20, and the third rail 130may be coupled with the basket 40. The second rail 120 is placed betweenthe first rail 110 and the third rail 130 for expanding the movabledistance of the basket 40.

The draw-out unit 100 may further include ball bearings 140, 150 placedbetween rails 110, 120, 130 for making the rails 110, 120, 130 smoothlyslide in/out. The ball bearings 140, 150 may include a first ballbearing 140 placed between the first and second rails 110 and 120, and asecond ball bearing 150 between the second and third rails 120 and 130.

The first ball bearing 140 may include at least one first ball 142, 144,and a first retainer 145 for holding the at least one first ball 142,144. The second ball bearing 150 may include at least one second ball152, 154, and a second retainer 155 for holding the at least one secondball 152, 154.

The first retainer 145 may include first ball installation units 146,148 for holding the first balls 142, 144. The first ball installationunits 146, 148 may be placed at a certain distance so that the firstballs 142, 144 may be taken at the certain distance. The first ballinstallation units 146, 148 may include a first upper ball installationunit 146 placed on the upper part of the first retainer 145 and a firstlower ball installation unit 148 on the lower part of the first retainer145.

The first balls 142, 144 may include the first upper ball 142 taken inthe first upper ball installation unit 146 and the first lower ball 144taken in the first lower ball installation unit 148. There may be aplurality of first upper and lower balls 142 and 144 taken in the firstupper and lower installment units 146, 148, respectively.

The first retainer 145 may be formed to be able to move along the firstrail 110. As shown in FIG. 4, the first retainer 145 may have the formof a short rail. To prevent the first retainer 145 from deviating fromthe first rail 110, the first rail 110 may include a first fastening rib111.

The second retainer 155 may include a second upper ball installationunit 156 and a second lower ball installation unit 158, and the secondballs 152, 154 may include the second upper ball 152 and the secondlower ball 154. The second retainer 155 may be formed to be able to movealong the second rail 120, and the second rail 120 may include a secondfastening rib 121 to prevent the second retainer 155 from deviating fromthe second rail 120.

The first and second fastening ribs 111 and 121 are arranged on thefirst and second rails 110 and 120, respectively, and the position ofthem may be adjusted to move the basket 40 as much distance as desired.

Referring to FIG. 5, a cross-sectional view of the rails 110, 120, 130are shown, in which connection units 112, 122, 132 extended in thevertical direction, and upper ends 114, 124, 134 and lower ends 116,126, 136 that bend toward one side may be included. The upper ends 114,124, 134 and lower ends 116, 126, 136 of the rails 110, 120, 130 maybend toward one side of the connection units 112, 122, 132 in theidentical form.

Specifically, all of the first rail 110, second rail 120, and third rail130 may be identically formed to include connection units 112, 122, 132,and upper and lower ends 114, 124, 134 and 116, 126, 136 which bendtoward one side.

Hereinafter, the connection unit, upper end, and lower end of the firstrail 110 are referred to as first connection unit 112, first upper end114, and first lower end 116, respectively; the connection unit, upperend, and lower end of the second rail 120 are referred to as secondconnection unit 122, second upper end 124, and second lower end 126,respectively; and the connection unit, upper end, and lower end of thethird rail 130 are referred to as second connection unit 132, secondupper end 134, and second lower end 136, respectively.

The first connection unit 112 may be formed to extend in the verticaldirection longer than the second connection unit 122 does, and thesecond connection unit 122 may be formed to extend in the verticaldirection longer than the third connection unit 132 does. That is, thefirst rail 110, the second rail 120, the third rail 130 decreasinglyextend in the vertical direction.

Accordingly, at least a part of the second rail 120 may be secured in aspace formed by the first upper and lower ends 114 and 116 which bendtoward one side of the first connection unit 112. Furthermore, at leasta part of the third rail 130 may be secured in a space formed by thesecond upper and lower ends 124 and 126 which bend toward one side ofthe second connection unit 122.

In other words, the first and second rails 110 and 120 may be arrangedsuch that the second upper end 124 is placed below the first upper end114 and the second lower end 126 is placed above the first lower end116. Furthermore, the second and third rails 120 and 130 may be arrangedsuch that the third upper end 134 is placed below the second upper end124 and the third lower end 136 is placed above the second lower end126.

As shown in FIGS. 3 and 4, the second upper and lower ends 124 and 126may be arranged to be in the same direction as that of the first upperand lower ends 114 and 116, and the third upper and lower ends 134 and136 may be arranged to be in the opposite direction of that of the firstupper and lower ends 114 and 116.

For the tub 20 and basket 40, the first and second rails 110 and 120 mayhave the upper ends 114, 124 and lower ends 116, 126 arranged toward thebasket 40, and the third rail 130 may be arranged toward the oppositedirection of the first and second rails 110 and 120, the inner side ofthe tub 20.

As to coupling of the draw-out unit 100, the first ball bearing 140 maybe fit into the first rail 110 such that the first upper ball 142 comesin contact with the bottom part of the first upper end 114 and the firstlower ball 144 comes in contact with the top part of the first lower end116. The first ball bearing 140 moves along the first rail 110 while thefirst ball 142, 144 is rotating, without being deviated from the firstrail due to the first fastening rib 111.

The first ball bearing 140 may be fit into the second rail 120 such thatthe first upper ball 142 comes in contact with the top part of thesecond upper end 124 and the first lower ball 144 comes in contact withthe bottom part of the second lower end 126. That is, the first upperball 142 is placed between the bottom part of the first upper end 114and the top part of the second upper end 124, and the first lower ball144 is placed between the top part of the first lower end 116 and thebottom part of the second lower end 126.

The second connection unit 122 may be arranged to be adjacent to thefirst connection unit 112, and the first upper and lower ends 114, 116and the second upper and lower ends 124, 126 may be placed in parallelin the same direction. Furthermore, the second rail 120 may includesecond fastening projections 128 at either end, which protrude towardthe first ball bearing 140. The second fastening projections 128 mayprotect at least one end of the second rail 120 from being deviated fromthe first ball bearing 140.

The second ball bearing 150 may be fit into the second rail 120 on theopposite side of the side on which the first ball bearing 140 is coupledwith, and the third rail 130 may be fit into the second ball bearing150. That is, the second upper ball 152 is placed between the bottompart of the second upper end 124 and the top part of the third upper end134, and the second lower ball 154 is placed between the top part of thesecond lower end 126 and the bottom part of the third lower end 136.

The third connection unit 132 may be arranged to be symmetrical to thesecond connection unit 122, and the second upper and lower ends 124, 126and the third upper and lower ends 134, 136 may be placed in parallel inopposite directions. Furthermore, the third rail 132 may include thirdfastening projections 138 that protrude toward the second ball bearing150, and the third fastening projections 138 may protect at least oneend of the third rail 130 from being deviated from the second ballbearing 150.

As discussed above, since the first rail 110, second rail 120, and thethird rail 130 may be formed to differ in length in the verticaldirection, the third rail 130 may be secured in the second rail 120,which may be secured in the first rail 110. Due to this, the first ballbearing 140 placed between the first rail 110 and the second rail 120may be formed to extend longer than the second ball bearing 150 placedbetween the second rail 120 and the third rail 130 in the verticaldirection.

Accordingly, the first balls 142, 144 and second balls 152, 154 may bealigned in the vertical direction, respectively. As shown in FIG. 5, thefirst upper ball 142 may be placed above the second upper ball 152, andthe first lower ball 144 may be placed below the second lower ball 154.In other words, because of the difference in length in the verticaldirection between the first and second ball bearings 140 and 150, all ofthe first balls 142, 144 and second balls 152, 154 may be placed in thevertical direction. This structure of the draw-out unit 100 may reducethe entire volume of the draw-out unit 100.

As shown in FIG. 5, the first rail 110 may be fixed on the inner side ofthe tub 20. As shown in FIG. 4, the first rail 110 may include afastening unit 113 for fastening the first rail 110 to the tub 20. Theremay be multiple fastening units 113 formed on the first connection unit112, and in FIG. 4, two fastening units 113 are shown to be separated ata certain distance.

The fastening unit 113 may be formed to protrude toward the inner sideof the tub 20 so as to securely contact the tub 20. A fastening opening172 may be formed on the fastening unit 113 for a fastening member 170to go through. In order for the fastening member 170 to go through thefirst rail 110 and the tub 20, an opening 22 (see FIG. 3) correspondingto the fastening opening 172 may be formed on the tub 20.

The fastening member 170 may have a male screw form with a head part, asshown in FIG. 5, but is not limited thereto and may have various forms.The fastening member 170 may go through the first rail 110 and the tub20 and be coupled with a fastening coupling member 178 placed on theouter side of the tub 20, thereby fastening the first rail 110 to thetub 20. Leakage protection members 174, 176 may be arranged on the innerand outer sides of the tub 20, respectively, to prevent cleaning waterfrom being leaked through the opening 22 (see FIG. 3) formed on the tub20.

FIG. 6 illustrates combination of the draw-out unit 100 and basket 40 ofthe dishwasher 1, according to an embodiment of the present disclosure.

As discussed above, the draw-out unit 100 may be coupled with thecoupling unit 60 of the basket 40, and specifically, the third rail 130may be coupled with the coupling unit 60. The coupling unit 60 mayinclude a moving unit 64 coupled with the third rail 130, and a handleunit 66 and an elevator unit 68 for moving the basket 40 up and down.

The elevator unit 68 may be fixed onto a side of the basket 40, and themoving unit 64 may be movably coupled with the basket 40. When the usergrips and takes down the handle unit 66, the elevator unit 68 ascendswith the basket 40 and the moving unit 64 maintains its originalposition while descending along the wire of the basket 40. Moving thebasket 40 up and down may lead to convenient loading of washable items.

The moving unit 64 may include a coupling projection 62 that protrudestoward the third rail 130, which may include a coupling groove 135 intowhich the coupling projection 62 is fit. There may be one or morecoupling projections 62 and corresponding coupling grooves 135, and inFIG. 6, two pairs of coupling projections 62 and coupling grooves 135are shown. The coupling projections 62 and coupling grooves 135 may eachbe located at a certain distance, and one of the coupling grooves 135 isnot shown in FIG. 6 because it is hidden by the second rail 120.

The coupling projection 62 may be formed to include a wide head part,and the coupling groove 135 may be formed as a passage narrower than thewidth of the head part of the coupling projection 62. Accordingly, thecoupling groove 135 may be formed as an opening having a groove formedat one end, and the coupling projection 62 may be inserted into thecoupling groove 135 through the groove.

The coupling groove 135 may be formed such that the coupling projection62 may be inserted from top to bottom of the coupling home 135 and befastened by a movement to a side. Accordingly, the coupling projection62 may be fastened in the vertical direction by being secured throughthe passage of the coupling groove 135. In this regard, in order tofasten the coupling projection 62 in the horizontal direction, thecoupling groove 135 may include a coupling member 160 detachably coupledwith the coupling groove 135.

The coupling member 160 may be fit in the coupling unit 133 thatprotrudes toward the basket 40 so as for the third rail 130 to form thecoupling groove 135. The coupling member 160 includes a top end 162 anda bottom end 166 to be stuck in the coupling unit 133, and the top end162 may include a hook. The coupling member 160 may also include aprojection unit 164 that protrudes to be stuck in the coupling groove135.

In other words, the coupling projection 62 may be fit through thepassage into the coupling groove 135, and the coupling member 160 may befit in the coupling unit 133 to secure the coupling projection 62. Thebottom end 166 of the coupling member 160 may be fit in the couplingunit 133, and the top end 162 of the coupling member 160 may be fastenedto the coupling unit 133 by being hooked up to the coupling unit 133.

According to the present disclosure, a slim draw-out unit may beprovided by aligning ball bearings in vertical direction, therebyincreasing the space utility of the dishwasher. Furthermore, thedurability of the dishwasher may be improved with three-tier assembly of‘C’-shaped rails, and smooth operation may be guaranteed with the ballbearings.

Several embodiments have been described but a person of ordinary skillin the art will understand and appreciate that various modifications canbe made without departing the scope of the present disclosure. Thus, itwill be apparent to those ordinary skilled in the art that thedisclosure is not limited to the embodiments described, which have beenprovided only for illustrative purposes.

What is claimed is:
 1. A dishwasher comprising: a tub; a basket arrangedinside the tub to load dishes; and a draw-out unit arranged on a side ofthe basket to guide the basket to be drawn out forward from the tub,wherein the draw-out unit includes first, second, and third rails, aplurality of first balls placed between the first and second rails, anda plurality of second balls placed between the second and third rails,and wherein the plurality of first balls and the plurality of secondballs are arranged in a vertical direction.
 2. The dishwasher of claim1, wherein the first, second, and third rails are each arranged to forma cross section including a coupling unit that extends in the verticaldirection and upper and lower ends that bend toward one side.
 3. Thedishwasher of claim 2, wherein the upper and lower ends of eachrespective rail of the first, second, and third rails bend toward oneside of the coupling unit of the respective rail in an identical form.4. The dishwasher of claim 3, wherein the coupling unit of the firstrail is formed to extend longer than the coupling unit of the secondrail in the vertical direction, and the coupling unit of the second railis formed to extend longer than the coupling unit of the third rail inthe vertical direction.
 5. The dishwasher of claim 4, wherein the firstand second rails are arranged such that the upper end of the second railis placed below the upper end of the first rail and the lower end of thesecond rail is placed above the lower end of the first rail, and thesecond and third rails are arranged such that the upper end of the thirdrail is placed below the upper end of the second rail and the lower endof the third rail is placed above the lower end of the second rail. 6.The dishwasher of claim 5, wherein the plurality of first balls includeat least one first upper ball placed between the upper end of the firstrail and the upper end of the second rail, and at least one first lowerball placed between the lower end of the first rail and the lower end ofthe second rail, and the plurality of second balls include at least onesecond upper ball placed between the upper end of the second rail andthe upper end of the third rail, and at least one second lower ballplaced between the lower end of the second rail and the lower end of thethird rail.
 7. The dishwasher of claim 6, further comprising: a firstretainer to hold the at least one first upper ball and the at least onefirst lower ball; and a second retainer to hold the at least one secondupper ball and the at least one second lower ball.
 8. The dishwasher ofclaim 3, wherein the upper and lower ends of the second rail arearranged toward a same direction as that of the upper and lower ends ofthe first rail, and the upper and lower ends of the third rail arearranged toward an opposite direction of that of the upper and lowerends of the first rail.
 9. The dishwasher of claim 1, wherein thedraw-out unit includes a first retainer placed between the first andsecond rails, and a second retainer placed between the second and thirdrails.
 10. The dishwasher of claim 9, wherein the first retainerincludes a plurality of first ball installation units that hold theplurality of first balls, and the second retainer includes a pluralityof second ball installation units that hold the plurality of secondballs.
 11. The dishwasher of claim 9, wherein the first retainer isinstalled to be able to move along the first rail, and the first railincludes a first fastening rib to prevent the first retainer fromdeviating from the first rail, and the second retainer is installed tobe able to move along the second rail, and the second rail includes asecond fastening rib to prevent the second retainer from deviating fromthe second rail.
 12. The dishwasher of claim 1, wherein the first railis attached onto an inner side of the tub, the third rail is coupledwith the basket, and the second rail is between the first and thirdrails.
 13. The dishwasher of claim 12, further comprising: a couplingunit on a side of the basket and being coupled with the third rail tomovably support the basket.
 14. The dishwasher of claim 13, wherein thecoupling unit includes a coupling projection that protrudes toward thethird rail, and the third rail includes a coupling groove into which thecoupling projection is fit.
 15. The dishwasher of claim 14, furthercomprising: a coupling member detachably coupled with the third rail soas to fasten the coupling projection fit into the coupling groove.
 16. Adishwasher comprising: a tub; a basket arranged inside the tub to loaddishes; a first rail fixed onto an inner wall of the tub; a second railinstalled to be able to move along the first rail; a third railinstalled to be able to move along the second rail and coupled with thebasket; a first ball bearing placed between the first and second railsand arranged to be able to move along the first rail; and a second ballbearing placed between the second and third rails and arranged to beable to move along the second rail.
 17. The dishwasher of claim 16,wherein the first ball bearing includes at least one first ball and afirst retainer to hold the at least one first ball, and the second ballbearing includes at least one second ball and a second retainer to holdthe at least one second ball.
 18. The dishwasher of claim 17, whereinthe at least one first ball and the at least one second ball arearranged in a vertical direction.
 19. A dishwasher comprising: a tub; abasket arranged in the tub to load dishes; and a draw-out unit installedbetween the tub and the basket, the draw-out unit including a pluralityof rails for guiding movement of the basket, wherein the plurality ofrails include a first rail attached to the tub, a second rail having oneside adjacent to the first rail, and a third rail having one sideadjacent to the second rail and another side coupled with the basket,and wherein the first rail is formed to extend longer than the secondrail in a vertical direction, and the second rail is formed to extendlonger than the third rail in the vertical direction.
 20. The dishwasherof claim 19, wherein each respective rail of the plurality of rails isformed to have a cross section that includes a coupling unit thatextends in the vertical direction and upper and lower ends that bendfrom the coupling unit of the respective rail in a same direction. 21.The dishwasher of claim 20, wherein the upper and lower ends of thefirst and second rails are arranged toward the basket, and the upper andlower ends of the third rail are arranged toward an opposite directionthan the upper and lower ends of the first and second rails.
 22. Thedishwasher of claim 21, wherein the draw-out unit includes a first ballbearing placed between the first and second rails, and a second ballbearing placed between the second and third rails.
 23. The dishwasher ofclaim 22, wherein the first ball bearing includes a first upper ballplaced between the upper end of the first rail and the upper end of thesecond rail, and a first lower ball placed between the lower end of thefirst rail and the lower end of the second rail, and the second ballbearing includes a second upper ball placed between the upper end of thesecond rail and the upper end of the third rail, and a second lower ballplaced between the lower end of the second rail and the lower end of thethird rail.
 24. A dishwasher comprising: a tub; a basket arranged insidethe tub; and a draw-out unit to guide the basket to be drawn out fromthe tub, the draw-out unit including a first rail having first andsecond sides, a second rail having first and second sides, a third railhaving first and second sides, and first and second ball bearings,wherein the first, second and third rails, and the first and second ballbearings are coupled together with the first side of the first railattached to the tub, the second side of the first rail adjacent to thefirst side of the second rail, the second side of the second railadjacent to the first side of the third rail, the second side of thethird rail coupled to the basket, the first ball bearing between thefirst and second rails, and the second ball bearing between the secondand third rails.